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JASEN Paula Veronica

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Título:

Effects of charged defects on MgH2 storage properties: A DFT Study

Autor/es:

F. GAZTAÑAGA; C. R. LUNA; M. SANDOVAL; F. ESCUDERO; G. BRIZUELA; J. JUAN; P. V. JASEN

Lugar:

Liverpool

Reunión:

Congreso; NANOENERGY2016; 2016

Resumen:

Magnesium hydride (MgH2) is considered a promising candidate asmaterial for hydrogen storage due to its low cost, availability andnon-toxicity, among others. However, the MgH2 activation energy for hydrogenkinetic desorption is relatively high [1]. One alternative for thisinconvenient is the addition of transition metals (TM) or defects likevacancies [2]. The goal of this study is to elucidate the chemical and physicalchanges by DFT calculations due to charged vacancies incorporation in MgH2.Particularly, were considered a H vacancy (VH), or a Mg vacancy (VMg)or a di-vacancy H-Mg (VH-Mg) in MgH2. For each vacancywere taken into account three possible charge states (q = +1, 0 and −1). Theresults show that the H vacancy formation is the most stable. And mostimportant band gap reductions are for neutral VH and negative VH , around 65.4 % and 68.8% respectively. Regarding to vacancyincorporation it can be seen that the changes more significant are in the bandgap zone, the valence and conduction band practically no change. Depending ofcharge states of them there is a band gap reduction and appears a magneticmoment. The most important induced magnetic moment is in the case of positive VMg (~0.74 µB).Moreover, theneutral VH and negative VH generate additionalstates in the band gap zone. This fact leads the system to an n-typesemiconductor behavior for  negative VH while in the rest ofcases are a p-type semiconductor. Finally, it can be concluded from the resultsthat charged vacancies incorporation improve the H dissociation and conduce tointeresting electronic properties.[1] R.Varin, T. Czujko, Z. Wronski, in Nanomaterials for Solid State HydrogenStorage, Chap. 2. Ed. Springer (Canada, 2009). [2] R. Yu and P.K. Lam, Phys Rev B, 37, 8730 (1988).

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